Question

Brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. Thermogenin is a channel for facilitated transport of protons across the membrane. What will occur in the brown fat cells when they produce thermogenin?
A) ATP synthesis and heat generation will both increase.
B) ATP synthesis will increase, and heat generation will decrease.
C) ATP synthesis will decrease, and heat generation will increase.
D) ATP synthesis and heat generation will both decrease.
E) ATP synthesis and heat generation will stay the same.

Answer 1

Answer:

C) ATP synthesis will decrease, and heat generation will increase.

Explanation:

The energy for ATPs synthesis in the mitochondria is generated by the  Proton Motive Force (PMF), which pumps protons across the intramembrane ;to set up electrochemical gradient for protons between the matrix and intramemebranes.

The energy generated  with the influx of protons down their electrochemical  gradients into the matrix is used for ATPs synthesis by the enzyme ATPase synthase.

Thermogenin however increases the permeability of inner mitochondria membrane to protons. Therefore the pumped protons in the intramemebranes leaked back into the mitochondria matrix,thus reducing the electrochemical gradient, inhibiting chemiosmosis, and therefore the energy for synthesis of ATPs by ATPase synthase enzyme in oxidation phosphorylation.

Therefore these uncoupling protein reduces the proton gradient meant for ATP synthesis.However because of the ability to generate heat  in the body as  non -shivering  mechanism of  heat generation, thermogenin will increase heat  in the brown fat cells.

Explanation:

Answer 2

B) ATP synthesis will kncrease and heat generation will decrease